CVE-2026-21619 — Unsafe Deserialization of Erlang Terms in hex_core

Description

Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.

This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.

Affected products

Vendor	Product	Affected	Fixed
hexpm	hex_core	0.1.0 – < 0.12.1	0.12.1
hexpm	hex	2.3.0 – < 2.3.2	2.3.2
erlang	rebar3	3.9.1 – < 3.27.0	3.27.0

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Debian

Security tracker ↗

Release	Package	Fixed in	Advisory
Debian 14	erlang-hex	2.4.2-2	—
Debian 14	rebar3	3.27.0-1	—
Debian 13	rebar3 +1	No fix yet	—
Debian 12	rebar3	No fix yet	—

Ubuntu